It's becoming more and more common: a hunter shoots what he thinks is a polar bear, only to discover it doesn't look quite right, with brown paws, huge claws, and a head the shape of a grizzly bear's. As climate change makes Arctic temperatures milder, grizzlies are moving north. At the same time, polar bears who have lost their icy habitats are moving south. When they meet in the middle, they often breed, creating these unusual looking hybrids, which are called either grolar bears or pizzly bears. But these are nothing like mules, a common hybrid animal that's known to be sterile. Scientists know that grolars are fertile because they've found the offspring of one: a bear shot by hunters in 2010 turned out to be the result of a union between a grolar bear and a brown bear.
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Key Facts In This Video
It's not true that if two animals can breed and produce fertile offspring, then they're the same species. Polar bears and grizzly bears are definitely not the same species. 01:25
We know that grolar bears are fertile, because in 2010, hunters shot a bear that was the offspring of a grolar bear and a brown bear. 01:52
The northern range of the grizzly bear has been increasing as temperatures get more mild, and as the ice melts, polar bears have been forced onto land. 02:07